Fuel injectors are required to deliver closely calibrated amounts of fuel in rapid succession under extreme conditions of pressure and temperature. Because of the great demands placed upon them, fuel injectors are typically quite complex and therefore expensive to manufacture. This invention utilizes the properties of an electro-rheological fluid in a unique way to minimize both the complexity and cost of fuel injectors while at the same time providing improved operational characteristics.
Electro-rheological fluids comprise slurries of finely divided hydrophilic solids in hydrophobic liquids. In the absence of an electric field these fluids behave in Newtonian fashion, but when an electric field is applied, the fluid becomes more viscous as the potential of the electric field is increased. This viscosity change continues until the fluid becomes substantially a solid upon application of a sufficient potential. The viscosity transformation of this fluid occurs in a very short period of time. An electro-rheological fluid thus provides an excellent medium for carrying out the present invention.
Electro-rheological fluids have been extensively used in clutches as disclosed, for example, by JAMES E. STANGROOM in U.S. Pat. Nos. 4,444,298 and 4,493,615.
Various forms of compression operated injectors have been proposed. In the more recent of these prior art devices, the injection of fuel can be controlled electronically. Typically these devices utilize solenoid valves to control the timing and the amount of fuel to be supplied.
Examples of compression operated injectors are included in U. S. Pat. Nos. Re. 23,476 to L. O. FRENCH; Re. 29,978 and 3,926,169 to LESHNER et al.; 1,995,a469 to S. D. OLSEN; 3,055,593, 3,060,912, 3,060,913, and 3,081,758 to C. H. MAY; 4,066,046 to R. E. MCALISTER; 4,095,580 to MURRAY et al.; 4,197,996 to D. S. GIARDINI; 4,247,044, 4,306,680, and 4,394,856 to SMITH et al.; and 4,427,151 to M. U. TRENNE.
The patents to GIARDINI, SMITH, and TRENNE utilize solenoid valves for fuel control.
Review of these prior art injectors shows them to be quite complex and expensive to manufacture. Additionally, because of the speed at which injectors must function, inertia of the moving parts, particularly solenoid valves, has a detrimental effect upon efficient performance.
It will be seen that these and other shortcomings of the prior art are effectively overcome by the present invention.
Because of its simplicity and unique operation when compared to conventional injectors the invention is particularly well suited for converting conventional carburetor engines to fuel injection, thus greatly improving performance. The invention permits the unrestricted flow of air through the intake manifold of a conventional internal combustion engine, thus providing a complete charge of air into each cylinder on each intake stroke. As the air is compressed during the compression stroke without the presence of fuel therein, there can be no detonation or preignition. Thus a great variety of either high or low octane fuels may be utilized by simply changing the timing of the injection of the fuel into the cylinders. Further, the device permits total control of the engine timing and output by precisely timed application of an electrical impulse.